1. Field of the Invention
The invention relates to a method of joining a first trouser part and a second trouser part by sewing a front trouser inseam and by inserting a zip fastener and a sewing unit for putting this method into practice.
2. Background Art
It is known practice from the publication of Pfaff Industrienahmaschinen GmbH entitled "PFAFF 200-04 Special Service" to sew together the associated strip of cloth on a left trouser forepart, the so-called left fly lining, and the associated area of the trouser forepart. The sewn-on strip of cloth is then folded over and the associated zip-fastener half, i.e. the left zip-fastener component, is sewn on. This strip of cloth is subsequently folded over again and the left joining seam is produced between the strip of cloth and the trouser forepart. Also, the sewing of the right strip of cloth having the right zip-fastener component, i.e. the associated zip-fastener half, on to the right trouser forepart takes place in several work cycles.
It is known from U.S. Pat. No. 4,534,067 to manufacture trouser flies in such a manner that an additional strip of cloth is also cut in one piece with each of the two trouser foreparts in the fly area and is then folded over and sewn together with the trouser forepart. In addition, a zip-fastener half, i.e. a zip-fastener component, is also sewn on. In the case of the left trouser forepart the outer edge is pressed inwards so that a four-layered design is formed in this case which is then stitched.
It is known from U.S. Pat. No. 4,911,091 to attach a strip of cloth provided with a zip fastener component to in each case one of two trouser foreparts such that the edge of the trouser forepart is folded over prior to being sewn together with the strip of cloth, that the trouser forepart with the folded-over edge and the strip of cloth are positioned relative to one another in a position which they occupy after being joined together. Then a zip fastener seam is sewn.
In addition to this it is known from U.S. Pat. No. 5,016,549 to fold over a rim of the strip of cloth and then the rim of the trouser forepart prior to the strip of cloth being joined to the trouser forepart, the strip of cloth being arranged above the trouser forepart and the folded-over rim of the trouser forepart and the folded-over rim of the strip of cloth being positioned in a position relative to each other which they will occupy after being joined together. Subsequently, the folded-over rims are brought into mutual contact. Then they are joined together with a single zip fastener seam.
It is known practice from the industrial sewing technique to sew together a first trouser part turned inside out and a second trouser part turned inside out and a zip fastener in such a way that first the first trouser part is joined to a half of the zip fastener by means of a first zip fastener seam, that subsequently the second trouser part equally turned inside out is joined to the second half of the zip fastener by means of a second zip fastener seam, the so-called J-seam, that then a front inseam is sewn and that subsequently a seam lock is sewn in the transition area from the zip fastener or the trouser fly formed by the latter, respectively, and the front inseam. This manual procedure requires a great number of different manipulations of the two trouser parts and the zip fastener.